On-board vehicle power is becoming essential for many different types of vehicles including, but not limited to, military vehicles, emergency response vehicles such as fire trucks and ambulances, and work trucks, to name a few. The concept of on-board vehicle power implies that the vehicle itself is being used as an electrical power generator. The electrical power source for an on-board vehicle power system may be provided by the vehicle's alternator and/or a single or multiple generator(s) placed under the hood or elsewhere on or in the vehicle. This on-board vehicle power system eliminates the need for carrying, hauling, or towing a separate motor-generator set into the field when electrical power is needed or required by the user. Additionally, depending upon the type of electrical load to be attached, a power electronics system may be necessary to convert the output of the generator/alternator into a usable form which may be described by characteristics and parameters such as direct current (DC), alternating current (AC), or multi-phase AC at a specific voltage level and frequency. The user may then connect the electrical load to the power electronics system and obtain an appropriate amount of power to be delivered to the electrical load.
For the alternator/generator to supply sufficient power, either the field current of the alternator/generator must be manipulated and/or the speed of the alternator/generator must be changed or modified. The field current is typically modified by a voltage regulator that adjusts the field current to maintain a constant output voltage. The present invention provides for controlling the engine speed for optimal engine performance as well. Typically, adjusting or modifying the field current is not sufficient to accommodate a broad range of electrical loads, resulting in the engine and/or the generator being overloaded and/or potential damage or failure. Therefore, the speed of the engine must be changed or modified to match the electrical load. Some form of a speed versus current (or power) relationship is typically available from the alternator/generator manufacturer. Changing or modifying the speed of the engine therefore requires some type of load sensor, information regarding the speed versus load relationship, an electronic processor, and an actuator that changes or modifies the speed of the engine when necessary. Existing patents do not provide the capability and flexibility of the present invention, which focuses on flexibility with total vehicle integration that can easily be adapted for different types of vehicles and for stationary and mobile applications.
U.S. Pat. No. 7,157,885, an inverter controlled generator set and method for controlling the same, utilizes a constant speed control mode until a set speed is reached and then a constant voltage control mode for speed control, so that the proper output voltage is achieved at the direct current (DC) source. In contrast, the present invention does not solely use a voltage-based speed control system.
U.S. Pat. No. 6,969,922, a transformerless, load adaptive speed controller, controls a variable speed engine/generator set. While the speed is controlled by the load current, it does not accommodate the control and integration of electronics for an on-board vehicle power system.
U.S. Pat. No. 5,311,063, an automatic load speed controller for an engine governor, is utilized for auxiliary or vehicle mounted electrical equipment. This invention is a voltage controller for multiple, selectable preset engine speeds and is not directly responsive to power demands as is the present invention. Additionally, the present invention allows for the entire continuous range of engine speeds from idle to maximum speeds and not certain preset engine speeds.
U.S. Pat. No. 5,216,350, a method and system for controlling an alternator, controls alternator responses based upon system load changes. This patent uses a microprocessor-based voltage regulator which defines a data matrix of system operation coefficients to match the load demand in determining the new field current required. Thus, the alternator output is modified by the field current. The present invention vastly differs from this patent in that, in the present invention, the field current is not the only element modified and total system integration is included and integral to the invention.
There accordingly remains a need in the art for an engine speed controller that provides total system integration and component control for an on-board vehicle power system so that an electrical load can be met tinder both stationary and mobile vehicle applications. The present invention provides such advantages.